Move GrProcessorSet into GrPipeline

Change-Id: Ibfa5e1adda3c32140590aa62a31d35654cef79dd
Reviewed-on: https://skia-review.googlesource.com/28187
Commit-Queue: Brian Salomon <bsalomon@google.com>
Reviewed-by: Robert Phillips <robertphillips@google.com>
diff --git a/src/gpu/ops/GrMeshDrawOp.h b/src/gpu/ops/GrMeshDrawOp.h
index 916806c..dc09e0c 100644
--- a/src/gpu/ops/GrMeshDrawOp.h
+++ b/src/gpu/ops/GrMeshDrawOp.h
@@ -67,7 +67,7 @@
     void onPrepare(GrOpFlushState* state) final;
     void onExecute(GrOpFlushState* state) final;
 
-    virtual void onPrepareDraws(Target*) const = 0;
+    virtual void onPrepareDraws(Target*) = 0;
 
     // A set of contiguous draws that share a draw token and primitive processor. The draws all use
     // the op's pipeline. The meshes for the draw are stored in the fMeshes array and each